Optical navigation sensors typically are used for computer input devices, e.g. optical mice. Optical navigation sensors detect motion by comparing successive patterns of light, e.g. “frames”, received by an array of photosensors. The optical navigation sensor then estimates which possible motion of the mouse is most likely to have occurred based on the relationship between the current frame and a previous frame.
However, the likelihood that the motion estimate from the optical navigation sensor is correct depends on the quality of the frames that are compared. High-quality frames exhibit distinct features that can be tracked from frame to frame. Low-quality frames have few distinct features.
Whenever the frame quality is low, the motion estimation by the optical navigation sensor may not reflect the motion of the optical sensor. Low quality frames can occur for several reasons. If the photosensors are exposed to too much light, then all of the photosensors may saturate at the maximum value. If the photosensors are exposed to insufficient light, then all of the photosensors may remain at the minimum value. If the surface over which the mouse operates lacks distinct features, then navigation is difficult. If the optical sensor is too far from the surface, then any distinctive features may be out of focus. If the optical sensor moves too quickly, there may be insufficient position overlap between frames for accurate motion tracking.